package _18_剑指OfferII;

import java.util.Arrays;

public class _098_剑指OfferII路径的数目 {


    public int uniquePaths(int m, int n) {
        int[] dp = new int[n];
        Arrays.fill(dp, 1);
        for (int i = 1; i < m; ++i) {
            for (int j = 1; j < n; ++j) {
                dp[j] += dp[j - 1];
            }
        }
        return dp[n - 1];
    }

    public int uniquePaths1(int m, int n) {
        int[][] dp = new int[m][n];
        dp[0][0] = 1;
        for (int i = 1; i < m; ++i) {
            dp[i][0] = 1;
        }
        for (int i = 1; i < n; ++i) {
            dp[0][i] = 1;
        }

        for (int i = 1; i < m; ++i) {
            for (int j = 1; j < n; ++j) {
                // 需要上一个数据，需要前面计算的右边的值
                dp[i][j] = dp[i - 1][j] + dp[i][j - 1];
            }
        }
        return dp[m - 1][n - 1];
    }

}
